#include <iostream>
#include <cmath>
using namespace std;
/*
1
1 
1*1 (2^0)

1 2
1
2
1 2
(1+2)*2 (2^1)

1 2 3
1
2
3
1 2 
1 3
2 3
1 2 3
(1+2+3)*4(2^2)

1 2 3 4
1
2
3
4
1 2
1 3
1 4
2 3
2 4
3 4
1 2 3
1 2 4
2 3 4
1 2 3 4

(1+2+3+4)*8 (2^3)


*/
int main( ){
    int cnt=0,x;
    long long sum=0;
    while(cin>>x){
        sum+=x;
        cnt++;
    }
    sum*=pow(2,cnt-1);
    cout<<sum;
    return 0;
}